Herbs and Supplements to Use Only With Caution

Most people can't tell when their blood pressure is high, which is why hypertension is called the "silent killer." In this case, what you don't know can hurt you. Elevated blood pressure can lead to a greatly increased risk of
heart attack
,
stroke
, and many other serious illnesses. Along with
high cholesterol
and
smoking
, hypertension is one of the most important causes of atherosclerosis. In turn, atherosclerosis causes heart attacks, strokes, and other diseases of impaired circulation.

The mechanism by which high blood pressure produces atherosclerosis is somewhat similar to what happens in a hose fitted with a high-pressure nozzle. All such nozzles come with a warning label that states, "Make sure to discharge pressure in hose after using." Unfortunately, many people frequently fail to pay attention to the warning and leave the hose puffed up with full pressure overnight. This rather common practice does not produce any immediate consequences. The hose doesn't develop leaks at the seams or burst outright on the first occasion you leave it untended. However, a garden hose that is frequently left under pressure will begin to age more rapidly than it would otherwise. Its lining will begin to crack, its flexibility will diminish, and within a season or two the hose will be sprouting leaks in all directions.

Similarly, when blood vessels are exposed to constantly high pressure, a similar process is set in motion. Blood pressures as elevated as 220/170 (systolic pressure/diastolic pressure), quite common during activities, such as weight lifting, do no harm. Only when excessive pressure is sustained day and night do blood vessel linings begin to be injured and undergo those unhealthy changes known as
atherosclerosis
.

Although it is important to lower blood pressure with all deliberate speed, only rarely does it need to be lowered instantly. In most situations, you have plenty of time to work on bringing down your blood pressure. However, that doesn't mean that you should ignore it. Over time, high blood pressure can damage nearly every organ in the body.

The best way to determine your blood pressure is to take several readings at different times during the day and on different days of the week. Blood pressure readings will vary quite a bit from moment to moment; what matters most is the average blood pressure. Thus, if many low readings balance out a few high readings, the net result may be satisfactory. However, it is essential not to ignore a high value by saying, "I was just stressed then." Stress is part of life, and if it raises your blood pressure once, it will do so again. To come up with an accurate number, you must include every measurement in your calculations.

In most cases, the cause of hypertension is unknown. The kidneys play an important role in controlling blood pressure, and the level of squeezing tension in the blood vessels makes a large contribution as well.

Lifestyle changes, such as quitting cigarettes, losing weight, and increasing exercise, can dramatically reduce blood pressure. Regarding exercise, one study found that engaging in aerobic exercise 60 to 90 minutes weekly may be sufficient for producing maximum benefits.
69
Another study found that taking four 10-minute "exercise snacks" of brisk walking per day significantly improves blood pressure.
78

For many years doctors advised patients with hypertension to cut down on salt in the diet. Today, however, the value of this stressful dietary change has undergone significant questioning. Considering how rapidly our knowledge is evolving, we suggest consulting your physician to learn the latest recommendations.

If lifestyle changes fail to reduce blood pressure, or if you can't make these alterations, many effective drugs are available. Sometimes you need to experiment with a few to find one that agrees with you.

Principal Proposed Natural Treatments

There are no herbs or supplements for hypertension with solid scientific support. However, the supplement coenzyme Q
10
(CoQ
10
)
and extracts from the herb
Stevia rebaudiana
have shown some promise in preliminary trials.

Coenzyme Q
10

The supplement CoQ
10
has shown promise as a treatment for high blood pressure, but the evidence that it works is not yet strong.

An 8-week,
double-blind, placebo-controlled
study of 59 men already taking medication for high blood pressure found that 120 mg daily of CoQ
10
reduced blood pressure by about 9% as compared to placebo.
7

In addition, a 12-week, double-blind, placebo-controlled study of 83 people with isolated systolic hypertension (a type of high blood pressure in which only the "top" number is high) found that use of CoQ
10
at a dose of 60 mg daily improved blood pressure measurements to a similar extent.
53

Also, in a 12-week, double-blind, placebo-controlled trial of 74 people with diabetes, use of CoQ
10
at a dose of 100 mg twice daily significantly reduced blood
pressure as compared to placebo.
62

Antihypertensive effects were also seen in earlier smaller trials, but most of them were
not
double-blind
and, therefore, mean little.
8-10

For more information, including dosage and safety issues, see the full
CoQ
10
article.

Stevia

The herb stevia is best known as a sweetener. Its active ingredients are known as steviosides. In a 1-year, double-blind, placebo-controlled study of 106 people with moderate hypertension (approximately 165/103), steviosides at a dose of 250 mg three times daily reduced blood pressure by approximately 10%.
12
Full benefits took months to develop. However, this study is notable for finding no benefits at all in the placebo group. This is unusual and tends to cast doubt on the results.

Benefits were also reported in a 2-year, double-blind, placebo-controlled study of 174 people with milder hypertension (average initial BP of approximately 150/95).
70
This study used twice the dose of the previous study: 500 mg three times daily. A reduction in blood pressure of approximately 6%-7% was seen in the treatment group as compared to the placebo group, beginning within 1 week and enduring throughout the entire 2 years. At the end of the study, 34% of those in the placebo group showed heart damage from high blood pressure (left ventricular hypertrophy), while only 11.5% of the stevioside group did, a difference that was statistically significant. No significant adverse effects were seen.

However, once again, no benefits at all were seen in the placebo group. This is a red flag for problems in study design. Both of these studies were performed in China, a country that has a documented history of questionable medical study results.
71

Furthermore, a study by an independent set of researchers failed to replicate these findings.
129
And, another study involving people with diabetes, as well as healthy subjects, found that stevia, at a dose of 250 mg three times daily, had no significant effect on blood pressure after 3 months of treatment.
130

Furthermore, a study by an independent set of researchers failed to replicate these findings.
129
And, another study involving people with diabetes, as well as healthy subjects, found that stevia, at a dose of 250 mg three times daily, had no significant effect on blood pressure after 3 months of treatment.
130

For more information, including dosage and safety issues, see the full
Stevia
article.

Relaxation Therapies

Although it seems intuitive that relaxation should lower blood pressure, the evidence for the benefits of
relaxation therapies
for treating hypertension is far from convincing.
In a review of 25 studies investigating various relaxation therapies (totaling 1,198 participants), researchers found that those studies employing a control group had no significant effect on lowering blood pressure compared to sham (placebo) therapies.
125

More specifically,
biofeedback
is widely advocated for treating hypertension. But, in an analysis of 22 studies, real biofeedback when used alone was found to be no more effective than sham (fake) biofeedback.
63
A subsequent review of 36 trials with 1,660 participants found inconsistent evidence for the effectiveness of biofeedback for treatment of hypertension in comparison to drug therapy, sham biofeedback, no intervention or other relaxation techniques.
141

However, not all studies have been unsupportive. A review of 9 randomized trials concluded that the regular use of transcendental meditation significantly reduced both systolic and diastolic blood pressure compared to a control.
126
Similarly, an analysis of 17 randomized controlled trials of various relaxation therapies found that only transcendental meditation resulted in significant reductions in blood pressure. Biofeedback, progressive muscle relaxation, and stress management training produced no such benefit.
127
In addition, a trial of 86 patients with hypertension suggested that daily, music-guided slow breathing reduced systolic blood pressure measured over a 24-hour period.
143

Prehypertension is a condition where blood pressure is elevated above what is considered normal, but
not the level of a hypertension diagnosis. A small randomized trial involving 43 patients with prehypertension showed that heart rate variability feedback reduced systolic blood pressure compared to slow abdominal breathing and control groups.
148

Other Proposed Natural Treatments

The Iranian herb
Achillea wilhelmsii
was tested in a double-blind trial of 60 men and women with mild hypertension.
38
The results showed that treatment with an
A. wilhelmsii
extract significantly reduced blood pressure readings.
In a double-blind study of 43 men and women with hypertension, use of a proprietary
Ayurvedic
herbal combination
containing
Terminali arjuna
and about 40 other herbs proved approximately as effective for controlling blood pressure as the drug methyldopa.
41

Although the research record is mixed,
15-21,104,137
it appears that
fish oil
may reduce blood pressure at least slightly.
56
Fish oil contains two major active ingredients, DHA (docosahexaenoic acid) and EPA (eicosapentaenoic acid). Some evidence suggests that it is the DHA in fish oil, but not the EPA, that is responsible for this benefit.
57

Several studies have found that
glucomannan
, a dietary fiber derived from the tubers of
Amorphophallus konjac
, may improve high blood pressure.
39-41
Other forms of fiber may be helpful as well.
79-80

Three preliminary double-blind studies found that
chocolate
(high in polyphenols) might help mild hypertension.
91,98,112
A review including several additional studies drew a similar conclusion.
136
A larger analysis of 20 trials studied 856 patients with and without hypertension. The trials compared flavonol-rich cocoa products to low or non-flavonol foods for an average of 4 weeks. Cocoa was found to significantly decrease systolic blood pressure in 20 trials and diastolic blood pressure in 19 trials.
147

Numerous studies have found weak evidence that
garlic
lowers blood pressure slightly, perhaps in the neighborhood of 5% to 10% more than placebo.
132-135
It remains unclear whether garlic supplements can help patients with high blood pressure safely eliminate or avoid antihypertensive medications.

People who are deficient in
calcium
may be at great risk of developing high blood pressure.
29,30,58
Among people who already have hypertension, increased intake of calcium intake might slightly decrease blood pressure, according to some but not all studies.
31,59
In an extremely large randomized, placebo-controlled trial involving 36,282 postmenopausal women, 1,000 mg of calcium plus 400 IU of vitamin D given daily did not significantly reduce blood pressure over a 7 year period in women with or without hypertension.
139
Weak evidence hints that use of calcium by pregnant mothers might reduce risk of hypertension in their children.
107

In a 30-day, double-blind, placebo-controlled study of 39 people taking medications for hypertension, treatment with 500 mg of
vitamin C
daily reduced blood pressure by about 10%.
33
Smaller benefits were seen in studies of people with normal blood pressure or borderline hypertension.
34,35
One double-blind study compared 500 mg, 1,000 mg, and 2,000 mg of vitamin C, and found an equivalent level of benefit in all three groups.
60
(Because of the lack of a placebo group, this study cannot be used as proof of effectiveness, only as a demonstration of the equivalence of the doses.) However, other studies have failed to find evidence of benefit with vitamin C.
36,37,66
This mixed evidence suggests, on balance, that if vitamin C does have any blood pressure lowering effect, it is at most quite modest.

Unexpectedly, one study found that a combination of vitamin C (500 mg daily) and grape seed
OPCs
(1000 mg daily) slightly
increased
blood pressure.
73
Whether this was a fluke of statistics or a real combined effect remains unclear.

There is mixed evidence on whether
soy protein
and their associated
isoflavones
are helpful for blood pressure.
92, 102
A comprehensive review of studies investigating the influence of phytoestrogens (including soy) on blood pressure found no meaningful effect.
131
However, another review found that soy protein alone could significantly reduce blood pressure.
136
See also the section on
Herbs and Supplements to Use Only With Caution
.

Three small double-blind, placebo-controlled studies found evidence that
melatonin
may slightly reduce nighttime blood pressure.
74,85,99

Getting adequate
vitamin D
may help prevent the development of hypertension.
45-49

The vitamin
folate
may help decrease blood pressure (as well as provide other heart healthy effects) in smokers.
67

Researchers have also studied
cinnamon’s
role in reducing blood pressure. In a randomized study involving 58 people with type 2 diabetes, 2 g of cinnamon daily reduced high blood pressure levels, as well as HbA1c levels (a measurement of blood sugar levels over time).
144

One study quoted as showing that a
traditional Chinese herbal formula
can reduce blood pressure actually failed to find any effect on blood pressure.
93
In a review of 26 published studies examining the effectiveness of Tai Chi for high blood pressure, 85% demonstrated a reduction in blood pressure. However, only five of these 26 studies were of acceptable quality.
128
A substantial study (192 participants) failed to find
acupuncture
helpful for high blood pressure.
100
However, another study, this one enrolling 160 people, did report benefit,
105,111
but it was small and also suffered from problems in its use of statistics. In a review of 11 randomized controlled trials on the subject, researchers determined that acupuncture’s ability to lower blood pressure remains inconclusive.
140

The alternative therapies
Hatha yoga
,
Qigong
,
113
and
Tai Chi76
have shown a hint of potential
68
benefit for high blood pressure, the mechanism of action probably being similar for each. A recent review of multiple studies investigating the effectiveness self-practiced Qigong, for example, concluded that it was more effective at lowering blood pressure than no treatment controls. However, it was no more effective than standard treatments for hypertension: antihypertensive medications or conventional exercise.
124
. Another review analyzed the benefits of yoga added to conventional hypertension treatment in 120 studies with 6,693 people. In the 48 randomized trials, specific yoga techniques were associated with significant blood pressure decreases. The studies suggest a correlation between yoga and lower blood pressure, but the study populations were extremely variable, making it difficult to draw specific conclusions.
149

In a 12-week study of 140 men and women with stage I hypertension,
chiropractic spinal manipulation
plus dietary change did not produce any greater benefit than dietary change alone.
77

For many years, the American Heart Association and other major foundations have recommended cutting down on saturated fat and increasing carbohydrates. However, growing evidence suggests that it is preferable to keep carbohydrate levels relatively low while replacing saturated fat with monounsaturated fats such as olive oil.
110
See the article on
Low-Carb Diet
for more information.

For a discussion of homeopathic approaches to high blood pressure, see the
Homeopathy
database.

Finally, because atherosclerosis is the main harm caused by hypertension, treatments discussed in the
Atherosclerosis
article should be considered as well.

Herbs and Supplements to Use Only With Caution

There is one highly credible case report of severe, dangerous hypertension caused by consumption of
isoflavones
made from soy during the course of a clinical trial on this supplement.
94
This is most likely a rare, highly individual response, but if it could occur with one person, it could occur with another as well.

As noted above, in one study, a combination of vitamin C and grape seed OPCs mildly increased blood pressure. In another study, use of vitamin E raised blood pressure in people with type 2 diabetes.
95

In addition, various herbs and supplements may interact adversely with drugs used to treat hypertension. For more information on this potential risk, see the individual drug article in the
Drug Interactions
section of this database.

Revision Information

This content is reviewed regularly and is updated when new and relevant evidence is made available. This information is neither intended nor implied to be a substitute for professional medical advice. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with questions regarding a medical condition.